Ground Source Heat Pump Questions

ham1sh

I'm hoping some of you guys can help me out with a few questions I have about aboput ground source heat pump systems.

Is it better to dig trenches and lay the pipes or go the bore hole route?
From what I can understand a bore hole would be more expensive, any ideas how much roughly? And which method provides the most effecient system?

Also as i have a young family that need baths etc every other night, would I also need to install solar panels to heat the water, or can the heat pumps these days, do it all? Can the solar panels also power the heat pump?

It is intended to install underfloor heating on the ground floor, but I haven't decided what to install on the first floor yet, possibly just standard radiators. Any advise on an alternative to radiators?

Cheers
Hamish

deckingman

I don't know a great deal - hopefully someone with more knowledge will jump in here.

AFAIK, ground source heat pumps are really only suited to under floor heating. I read somewhere that the water doesn't get hot enough for conventional radiators (which work more by convection) or domestic hot water use. It takes qite a bit of electricity to run them.

I think you get out something like 4 times what you put in, so say if you needed say 8kW of heat, you need to supply 2 kW of electricity. If that's the case, then you need to work out how heat you need and then calculate how much power will be required from your solar system. Don't forget that you'll need to store power in batteries if you want to run the heat pump directly from the solar (like when it's dark).

ham1sh

Thanks Deckingman.
After reading up a bit more, I don't think solar is going to give sufficient output to drive the heat pump. Some of these pumps require a 3 phase supply apparently.
I'm still hoping to use the heat pump for radiators upstairs, (even though it's not ideal) as I can't think of a suitable alternative.

I suppose the next step will be to get a company round to give me a quote and some advice. There are a few companies up here (NE Scotland), that do this type of work, although I don't know how good they are. In fact I don't know anybody that has this type of system, so it's going to be a leap of faith, in more ways than one.

Thanks
Hamish

setjellyfish

I was looking at heat pumps and when I worked out all the figures it's 4 times more expensive to install compared to getting a new gas boiler and marginally less expensive to run. All in all not worth the hassle yet.

mrm3

'only marginally less expensive to run' seems wrong ?

I thought the point when installed heating is virtually free !

setjellyfish

That's what I thought too but you still use electric to run the heat pump  and when you work out the amount of electric you need to use compared to the gas used to run a boiler it's nearly the same cost. It's like all these new 'green' techs great in principle but expensive to install and take decades to recoup the costs.

gavan

That doesn't sound right - got any figures to back up your claim?

robh2002

Unless you can get extremely good heat pump systems with a very high coefficient of performance (COP) then the costs could very well be close to that mentioned above compared to gas.

Burning gas in a new boiler will be done with a thermal efficiency of up to around 90%. Generating electricity to run the heat pump (say using a gas turbine, coal, nuclear etc.) might do so at an efficiency of say 30-40% (some higher - some lower). While the heat pump generates more heat that it uses in electricity you still have to factor in the efficiency of the electricity generation in the first place and its cost. Electricity is around 2 - 3x more expensive than gas (VERY roughly!) because of the efficiency of generation.

Perhaps very new heat pumps might have a higher COP making up for the low electricity generation efficiency, but if you have access to gas, it is usually cheaper to use this. If you have no gas then a heat pump will definitely be the way to heat a house.

Hope that makes sense - been a long day...

setjellyfish

We've got an article on our website that might help...
Ground source heat pumps - Heat pumps & ground loops - Energy Saving Trust

Clare
The Energy Saving Trust
Energy Saving Trust - Energy Efficiency & Energy Conservation to combat Climate Change

ham1sh

I'm not claiming anything I was really hoping it was going to be cheaper and was already to dig up my garden. I did have figures but it all got binned along with the idea.